1. Field of the Invention
The present invention relates to a liquid crystal display device which is suitable as a display section of a portable or a stationary electronic apparatus, and an electronic apparatus including the liquid crystal display device. More specifically, the present invention relates to reinforcement in strength of, for example, a slim liquid crystal display device. Further, the present invention relates to reinforcement in strength of a stationary electronic apparatus including a large-sized liquid crystal display device such as a liquid crystal TV (television) or the like as one example, when carrying or handling the stationary electronic apparatus.
2. Description of the Related Art
In recent years, a liquid crystal display device is commonly used as a display (display section) for a portable electronic apparatus (hereinafter referred to as “mobile apparatus”). The liquid crystal display device includes a liquid crystal display panel; the liquid crystal display panel is commonly arranged in such a manner that a pair of transparent substrates made of glass or the like sandwich a liquid crystal layer. The liquid crystal display device is widely used in a display for a notebook computer, and also a mobile apparatus such as an information mobile terminal (PDA: Personal Digital Assistant) and a mobile phone. This is because the liquid crystal display device excels in mobility, and also has low power consumption. From a point of mobility and convenience, the mobile apparatus is required to be thin, lightweight and strong.
The liquid crystal display device has also been commercialized as a stationary large-sized apparatus such as a slim TV, and such a liquid crystal display device is becoming widely spread. In recent years, demands for reducing thickness and weight of such stationary products have also been increasing. Therefore, as similar to the mobile apparatus, the large-sized liquid crystal display device requires to be, not only thin and lightweight, but also sufficiently durable to external pressure applied when carried, handled or generally used.
In response to such demands, approaches have been made to reduce the thickness and weight of the liquid crystal display device. However, attainment of strength has been difficult in line with such an approach.
That is to say, generally, the liquid crystal display device adopts an arrangement in which a chassis 107 is formed on a periphery of a light guiding plate 102b, as illustrated in FIG. 16. The chassis 107 serves as a supporting member of the light guiding plate 102b. However, since the light guiding plate 102b has become thin in response to the reduction in thickness and weight of a liquid crystal module, and since a housing of the liquid crystal display device is made of resin such as PMMA (PolyMethyl MethAcrylate), the liquid crystal display device is not strong in rigidity. Therefore, in a case where there is a step 107a generated due to the chassis 107 on a back side of the light guiding plate 102b, this step 107a becomes a cause of a partial warp in a liquid crystal display panel 101 as illustrated in FIGS. 17A and 17B. In some cases, breakage of the liquid crystal display device occurs as a result of this arrangement.
Moreover, from a layout point of view, many of the liquid crystal modules and the mobile apparatuses which include the liquid crystal module provide a driving circuit for driving the liquid crystal display panel, and/or another system, a battery, and the like on the back side of the liquid crystal module. Various chip parts that are mounted on the driving circuit have uneven planes, and a cover and a spacer for protecting the various chip parts from external pressure also have uneven planes. Therefore, the liquid crystal module and the mobile apparatus that include the liquid crystal module are arranged in such a manner that when a load is placed on the uneven planes, the liquid crystal display panel partially warps easily and readily.
In a case where the light guiding plate of the liquid crystal module is thin, and further has protrusions and depressions on its back side, the liquid crystal display panel made of glass may warp and break due to (i) pressure applied from a display surface, (ii) pushup force from a driving circuit board at a time when the liquid crystal module is dropped, or further (iii) a warp generated in the liquid crystal module at a time when the liquid crystal module is dropped. Accordingly, any liquid crystal module that has the possibility that any one of the foregoing may occur is considered as having insufficient mechanical strength as a product. Therefore, some kind of measure, particularly for improving rigidity of a housing section or the like is required for the liquid crystal display panel that is mounted in an apparatus such as the mobile apparatus that can be carried and the large-sized liquid crystal display device.
In response to this, many of the mobile apparatuses which use the liquid crystal display panel such as a tablet personal computer are designed to have a protection plate, which makes it difficult for external force such as an impact or the like to be applied on the liquid crystal display panel. Such arrangement has been adopted in many of the mobile apparatuses.
However, adoption of such arrangement requires a protection board that has a sufficient rigidity. Moreover, the arrangement is one in which a slight gap is formed between the liquid crystal display panel and the protection plate, so as to prevent force from being passed to the liquid crystal display panel. As a result, a measure for thickening the protection plate and/or the gap is required. Such measure is contrary to obtainment of a thin and lightweight end product, therefore, such measure is not preferable.
For example, Japanese Unexamined Patent Publication No. 142404/2001 (Tokukai 2001-142404) suggests an information display device as illustrated in FIG. 18A, including: a plate-shaped liquid crystal display panel 201 which serves as an information display; a metal plate 203 which is of a same size as the liquid crystal display panel 201 and is retained so as to cohere to a back surface of the liquid crystal display panel 201; a driving circuit board 204 provided on an opposite side of the liquid crystal display panel 201 on the metal plate 203, the driving circuit board 204 mounting a driving circuit for driving at least the liquid crystal display panel 201; an upper case (not illustrated) with an opening enabling visual perception of a display displayed on the liquid crystal display panel 201; and a lower case (not illustrated) for storing the liquid crystal display panel 201, the metal plate 203, and the driving circuit board 204, together with the upper case.
However, the conventional display device of Japanese Unexamined Patent Publication No. 142404/2001 (Tokukai 2001-142404) does not give consideration to a load placed on or an impact to the display surface and the back side of the display surface. For example, there is the problem that breakage may occur caused by a pressure load applied from the surface of the liquid crystal display panel 201, a pushup from a back side of the liquid crystal display panel 201, and/or a partial warp due to the change in shape.
More specifically, for example, as illustrated in FIG. 18B, a load placed on an upper side of the liquid crystal display panel 201 causes the metal plate 203 to warp, and effected by this warp, the liquid crystal display panel 201 and the light guiding plate 202b also warps. As a result, the liquid crystal display panel 201 breaks. The causes of this warp are, for example, the flexibility of the metal plate 203 caused by its thinness, and a step 204a formed between the metal plate 203 and the driving circuit board 204. These cause the liquid crystal display panel 201 and the like to bend at the step 204a. 
Alternatively, there also is a problem such that if a driving circuit board 303 provided at a back side of the light guiding plate 302b has protruding sections 303a on a side of the driving circuit board 303 closer to the light guiding plate 302b as illustrated in FIG. 19, which protruding sections 303a are of a circuit part such as a coil or the like, the protruding sections 303a comes in contact with the light guiding plate 302b under an impact in a case where the liquid crystal display device is dropped. This causes a breakage of the protruding sections 303a or the light guiding plate 302b. 